Page 51 - Plastics News March 2017

TEChNoLoGy

Polymer additive to revolutionize plastics recycling

olymer additive could revolutionize plastics recycling of the group’s tetrablock additive held so well that the
Paccording to a study done by Geoffrey Coates who is plastic strips broke instead. People have done things
the Tisch University Professor of Chemistry and Chemical like this before,” Coates said, “but they’ll typically put
Biology Polyethylene (PE) and polypropylene (PP), 10 percent of a soft material, so you don’t get the nice
which account for two-thirds of the world’s plastics, plastic properties, you get something that’s not quite as
have different chemical structures and thus cannot be good as the original material.” “What’s exciting about
repurposed together. Or, at least, an efficient technology to this,” he said, “is we can go to as low as 1 percent of
meld these two materials into one has not been available in our additive, and you get a plastic alloy that really has
the last 60 years. That could change with a discovery out of super-great properties.” Not only does this tetrablock
Geoffrey Coates lab. Coates is the Tisch University Professor polymer show promise for improving recycling, Eagan
of Chemistry and Chemical Biology. He and his group have said, it could spawn a whole new class of mechanically
collaborated with a group from the University of Minnesota tough polymer blends. Financial support for the
to develop a multiblock polymer that, when added in collaboration between Coates’ group and the group led
small measure to a mix of the two otherwise incompatible by Frank Bates, University of Minnesota professor of
materials, create a new and mechanically tough polymer. chemical engineering and materials science, came from
the Center for Sustainable Polymers, a National Science
Foundation (NSF) Center for Chemical Innovation. “NSF
believed in our idea of bringing together these pieces
to be able to do science as a whole that we can’t do
individually,” Coates said.

Creating novel two-
dimensional (2D) graphene-

like polymer sheets

A research team from the National University of
Singapore (NUS) has successfully pushed the frontier
of polymer technology further by creating novel two-
Their work is detailed in a paper, “Combining polyethylene dimensional (2D) graphene-like polymer sheets. The
and polypropylene: Enhanced performance with PE/iPP novel polymer sheets synthesized by the NUS team are
multiblock polymers,” published online in Science.James unique because of their good electrical conductivities
Eagan, a postdoctoral researcher in Coates’ group, is and highly regular, sub-nanometer sized pores, which
lead author of the paper. other collaborators included can be used to store sodium ions efficiently and safely
researcher Anne LaPointe and former visiting scientist in sodium ion batteries. Sodium ion batteries are a type
Rocco DiGirolamo. Scientists for years have tried to develop of rechargeable metal-ion battery that uses sodium
a polymer that does what Coates, LaPointe and Eagan have ions as charge carriers. As there is an abundance of
achieved. By adding a miniscule amount of their tetrablock sodium, sodium ion batteries are cheaper to produce
(four-block) polymer – with alternating polyethylene and than lithium ion batteries. However, the disadvantage
polypropylene segments – the resultant material has is that they do not last long. The 2D polymer developed
strength superior to diblock (two-block) polymers they by Loh and his team can be mass produced at low
tested. In their test, two strips of plastic were welded cost for use as the electrode for sodium ion batteries,
together using different multi-block polymers as adhesives, enabling such batteries to perform at high capacity for
then mechanically pulled apart. While the welds made with thousands of charge cycles.
diblock polymers failed relatively quickly, the weld made

51 March 2017 | Plastics News